Authors:

Sergei Urazhdin(West Virginia University)

Stuart Tessmer(Michigan State University)

Theodora Kyratsi(Northwestern University)

Mercouri Kanatzidis(Northwestern University)

We performed cryogenic scanning tunneling microscopy and spectroscopy
measurements of the surface and defect states in topological insulators
Bi2Se3 and Bi2Te3. Our measurements demonstrate gapless surface states in
both materials. While Bi2Te3 is naturally p-doped, we observed both p- and
n-doped regions on the cleaved surface. These observations can be correlated
with local cleaving within quintuple layers seen from topography
measurements, suggesting a new route for surface doping of topological
insulators. We also describe unique clover-shaped defects states appearing
inside the bulk valence band. Our band structure calculations show that
these states originate from a combination of bonding anisotropy and surface
band bending, resulting in formation of subsurface resonances.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.D42.12